In the field of thermal spray, a range of different types of powder feeders are utilized to convey a spray powder material via a powder hose to a spray gun. Powder feeders are generally either mechanical or pneumatic in design. Mechanical powder feeders rely on feeding screws (augers), metering blades, or other actuators that selectively dose the powder, which is then propelled into a collecting cone and further downstream into a powder hose.
Both mechanical and pneumatic powder feeders are prone to producing pulsating powder flows for a variety of reasons. One common cause of pulsation is undesirable accumulation of powder inside the collecting cones or voids and pockets of the metering mechanism of the powder feeder. During regular operation, especially at high feed rates, powder can accumulate inside a collecting cone, temporarily blocking the flow, until it is pushed through by the pressure of the carrier gas, creating a spike in the resultant powder flow. Similarly, powder can also accumulate in the internal pockets, voids, or channels of the powder feeder or its metering mechanism, and then get dislodged and be carried downstream as one mass, similarly producing a temporary spike in the powder flow. All powders can create these undesirable aberrations in normal operation, but clumping powders are particularly prone to creating this type of issue. The resultant powder flow is often unsteady, containing ebbs and spikes that can be highly detrimental to achieving a uniform coating quality.
Therefore, there is a need for a powder feeder for a thermal spray application that can convey a powder through a powder hose uniformly, free of pulsation, and unaffected by the flow characteristics of the powder being conveyed. The device of the present disclosure accomplishes at least the above objectives and overcomes the above-described or other disadvantages of conventional powder feeders.